The present invention relates to an original sheet circulation apparatus of copying machines.
In a diazo copying machine and the like, an original sheet and a photosensitized paper are superimposed on each other and are then inserted into a sheet inlet portion of the diazo copying machine and are exposed to light to form a latent image on the photosensitized paper. The latent image bearing photosensitized paper is then separated from the original sheet and the latent image is then developed so that a copy of the original is obtained, while the original sheet is recovered into a predetermined section of the copying machine. In the copying machines of this type, when multiple copies are made from one original, the original sheet is superimposed on a new photosensitized paper each time the original sheet is discharged from an original sheet outlet portion of the copying machine, and both the original sheet and the new photosensitized paper are again inserted into the above-mentioned sheet inlet portion.
In contrast with a low class copying machine of the above-mentioned type, a conventional high class copying machine is provided with an original sheet circulation apparatus which is capable of circulating the original sheet automatically for making multiple copies from the original sheet once the original sheet is inserted into the copying machine. However in the conventional high class copying machines, a comparatively large original sheet circulation apparatus is built in the copying machine, and its mechanism is rather complicated due to the use of a negative pressure suction apparatus and sheet transportation belts. Therefore, the conventional high class copying machine tends to become over-sized and expensive.